Dry matter intake

Dry matter intake by NRC method, with formulas at different temperatures for different breeds

1. Factors affecting Dry Matter Intake of cow Vishnu Vardhan Reddy.P TVM/2015-029 Department of Animal nutrition College of Veterinary Science, Tirupati Sri Venkateswara Veterinary University

2. Dry Matter Intake Dry matter intake (DMI) is fundamentally important in nutrition because it establishes the amount of nutrients available to an animal for health and production . P hysical fill of the reticulorumen (Allen, 1996; Mertens , 1994 ) Metabolic-feedback factors ( Illius and Jessop, 1996 Mertens , 1994) Oxygen consumption ( Ketelaars and Tolkamp , 1996)

3. E quations for predicting DMI Lactating Cows 1971 edition ( NRC, 1971) simply recommended feeding ad libitum during the first 6 to 8 weeks of lactation, and then feeding to energy requirements after that for lactating dairy cows . In 1978 ( NRC, 1978) body weight and 4 percent fat-corrected milk were factors used to estimate DMI, which ranged from 2 to 4 percent of body weight.

4. 1989 edition ( NRC, 1989 ) predicted DMI on the basis of energy requirement theory. DMI ( kg)= NEL included requirements for maintenance, milk yield, and replenishment of lost weight . Suggested 18 percent reduction of DMI during the first 3 weeks of lactation. DMI reduction of 0.02 kg per 100 kg of body weight for each 1 percent increase in moisture content of the diet above 50 percent when fermented feeds were being fed. NEL concentration of diet (Mcal/kg) NEL required (Mcal )

5. 1989 edition (NRC, 2001) published equation based on data published in the Journal of Dairy Science (1988-1998) and data from Ohio State University and the University of Minnesota (May, 1994) DMI (kg/d ) = (0.372 X FCM + 0.0968 X ) X (1- Temperatures >20 ° C, DMI X (1 - ((C° - 20) X 0.005922)) Temperatures <5 ° C, DMI /(1 - ((5 – C°) X 0.004644)).  

6. Growing Heifers DMI (kg/d) = ( X (0.2435 X NEM - 0.0466 X 0.1128)/NEM) NEM is net energy of diet for maintenance (Mcal/kg). The adjustment factor for above equation based on days of gestation is = [1 + ((210 - DG) X 0.0025)] where DG = day of gestation .  

7. Nutrients and feeding management related to DMI of lactating dairy cows

8. Moisture: A decrease in total DMI of 0.02 percent of body weight for each 1 percent increase in moisture content of the diet above 50 percent was indicated when fermented feeds. Most high moisture feeds are fermented, and the decrease in DMI when they are fed is generally thought to result from fermentation end products and not water itself . However, DMI was not affected by soaking grain . Though dietary DM content and DMI are conflicting there is no optimum DM content of the diet for maximum DMI is apparent .

9. Neutral Detergent Fiber: NDF be used to define the upper and lower bounds of DMI . At high NDF concentrations in diets, rumen fill limits DMI whereas, at low NDF concentrations energy intake feedback inhibitors limit DMI . Studies showed a general decline in DMI with increasing NDF concentrations in diets when diets exceeded 25 percent NDF. However, lactating cows fed high energy diets ranging in NDF from 25 to 42 percent of DM, less than 1 percent of the variation in DMI was accounted.

10. Forage to Concentrate Ratio: The DMI increased with increasing concentrate in diets regardless of forage type . Digestible DM also increased with increasing concentrate in the diet . C ows fed a 74 percent forage diet (2:1 alfalfa silage to corn silage) consumed 2.7 kg less DM per day than cows fed a diet containing 50 percent forage. In general, increasing concentrate in diets up to about 60 percent of the DM increased DMI.

11. Fat: Assuming that cows consume DM to meet their energy requirements often less DM is consumed when fat replaces carbohydrates as an energy source in diets. Fats may also decrease ruminal fermentation and digestibility of fiber and leads to rumen fill and decrease the rate of passage. For the diets containing 5 to 6 percent total fatty acids , the addition of oilseeds and hydrogenated fatty acids to diets resulted in a quadratic effect on DMI with minimums occurring at 3 and 2.3 percent added fatty acids, respectively .

12. A s the proportion of unsaturated fatty acids in the fat source increased, DMI generally decreased . Increased saturated fatty acids usually reduces the negative ruminal effects associated with fats . But increased DMI with fat addition is observed when fat substituted for grain due to lower heat increment during periods of heat stress and a reduction in propionate inhibition.

13. Cow behavior, management, and environmental factors affecting feed intake

14. Eating Habits and Cow Behavior: Behavior at the feed bunk is often affected by social dominance . Dominant cows, usually older and larger, tend to spend more time eating than do cows with a lower social rank in a competitive situation , such as when bunk space is restricted. In a situation of competition for feed, cows consume slightly more feed but do it in less time per day than when there is no competition and access to feed is ample.

15. Average time spent at the feed bunk (3.7 hours/day) did not decrease until only 10 cm of space per cow was available. Rapid growth in growing heifers fed a total mixed diet could be maintained in young heifers ( 4 to 8 months old ) with 15 cm of bunk space . But, by the age of 17 to 21 months , feed bunk space needed to be similar (47 cm) to that recommended for lactating cows .

16. Cattle prefer mangers that allow them to eat off a smooth surface in a natural grazing position. evidence showing that cows eating with their heads down produce 17 percent more saliva than cows eating with their heads in a horizontal position.

17. Weather: The thermal neutral zone of dairy cattle is about 5 to 20 ° C, but it varies among animals . A decrease in DMI up to 55 percent of that eaten in the thermal neutral zone along with an increase of 7 to 25 percent in maintenance requirement has been reported for cows subjected to heat stress. Water consumption of cattle increases as ambient temperature increases up to 35° C , but further temperature increases decrease water consumption because of inactivity and low DMI.

18. P regnant multiparous middle to late-lactation Holstein cows decreased DMI more ( 22 percent ) than primiparous cows ( 9 percent ) at the same stage of lactation and pregnancy when subjected to heat stress .

19. Feeding Method—Total Mixed Ration vs. Individual Ingredient: Nutrients can be effectively supplied by feeding either a total mixed ration (TMR) or individual ingredients. TMR allows for the mixing of all feed ingredients together based on a prescribed amount of each ingredient. When animals fed as TMR without sorting of ingredients, better rumen fermentation and a better use of nutrients should occur than feeding of separate ingredients.

20. Feeding Frequency: It has been suggested that increasing the frequency of offering feed to cows increases milk production and results in fewer health problems . O n feeding frequency that changing from one or two offerings of feed per day to four increased average daily gain of cattle by 16 percent, increased feed use by 19 percent, milk fat of 7.3 percent and milk production 2.7 percent . Improvements in gain were greatest when cattle were fed high-concentrate diets.

21. Sequence of Feeding: The feeding of highly fermentable carbohydrates to cows that have been without feed for over 6 hours could cause acidotic conditions in the rumen depressing feed intake and fiber digestion . Feeding forage(s ) as the first feed in the morning before other feedstuffs would allow for the formation of a fiber mat in the rumen and provide buffering capacity in the rumen from both the forage and the increased salivation associated with forage consumption.

22. Access to Feed: Maximal DMI can only be achieved when cows have adequate time for eating . There is a considerable difference in eating behavior between cows in a non-competitive feed environment and competitive feed environment. limiting the access of feed to 8 hours a day decreased milk production of cows averaging about 25 kg/day by 5 to 7 percent compared with cows that had free-choice access to feed.

23. Thank you Vishnu Vardhan Reddy.P TVM/2015-029